Depressive symptom trajectories are associated with mental health outcomes in young adulthood

Purpose: To describe developmental trajectories of depressive symptoms in adolescents and to examine the association between trajectory group and mental health outcomes in young adulthood. Methods: Depressive symptoms were self-reported every three months from grade 7 through grade 11 by 1293 adolescents in the Nicotine Dependence in Teens (NDIT) study. A post-secondary school survey was administered in young adulthood (average age 20.4 years, SD=0.7, n=865). Semi-parametric growth modeling was used to identify sex specific trajectories of depressive symptoms. Results: The best-fitting model for both boys and girls included three distinct trajectory groups. Fifty percent of boys and 29% of girls exhibited low and decreasing levels of depressive symptoms; 14% of boys and 28% of girls exhibited high and increasing levels of depressive symptoms. Trajectory group was a statistically significant predictor of depression, stress, and self-rated mental health in young adulthood in boys and girls. Boys, but not girls, with high and increasing levels had a statistically significant increase in the likelihood of seeking psychiatric care. Conclusions: In contrast to examining mean scores, the trajectory approach identified a substantial percentage of both boys and girls with decreasing depressive symptoms scores during adolescence. Because early depressive symptoms predict mental health problems in young adulthood, monitoring adolescents for depressive symptoms may help identify those most at risk and in need of intervention.